While excavating the pre-hispanic Pachacama site on the Pacific coast of Peru, a team of archaeologists from Brussels recently made a huge — and eerie — discovery. Apparently, the team unearthed a burial chamber filled with more than 80 mummies and a dozen curiously placed infant remains. The skeletons of the newborns appear to have been arranged around the perimeter of the tomb, in what scientists say may have been a sacrificial ceremony.

Dating back to 1,000 AD, the 66-ft.-long, oval-shaped burial chamber somehow evaded pillagers, and remains in surprisingly good condition. Alongside the skeletons lie other ancient artifacts, including ceramics, animal remains, and copper, according to Science Daily News.

Though still in the early stages of research, the scientists say the area may have been a type of healing center, because some of the remains show signs of illness. Located approximately 19 miles outside of Lima, the Pachacama site is under consideration by UNESCO as a possible World Heritage site.

As the ancient home of one of South America’s largest Inca and Hurai civilizations, the site has attracted copious attention from researchers over the years. Excavation on the site began in the late 1800s with the arrival of a German archaeologist, Max Uhle. In the past 20 years, archaeologists have made a number of remarkable discoveries in Pachacama, including several pyramids and a cemetery.